This invention relates to a dryer such as a clothes dryer for articles which are held in a container during the drying and provides a heating means in the air duct to the container and an air mixing baffle in the duct in combination with an ambient air inlet opening so that the cooler ambient air will be mixed with the heated air from the heater to provide a uniform temperature throughout the flowing air stream and to reduce the temperature thereof before directing the air into the drying container.
The invention is particularly important for dryers using electric heating means and particularly an electric heater having an expanded metal resistance unit because under such conditions the heated air tends to stratify in streamline flow with the various strata having different temperatures which tends to cause hot spots or overheated areas in the duct particularly at the region of the entrance to the drying container. The dryer of this invention successfully prevents this.
The most pertinent prior art of which applicants are aware is as follows: U.S. Pat. Nos. 3,651,304; 3,798,417 and 3,860,789. These patents disclose electric resistance heating elements of the expanded metal type. However, none of these patents discloses the combination of this invention as claimed in the appended claims.
U.S. Pat. No. 1,579,852; 1,996,253 and 2,422,825 each disclose a dryer having heating means and means for mixing the heated air with ambient air. U.S. Pat. No. 2,635,354 discloses a baffle for directing ambient air into a stream for mixing with the heated air before the mixture enters the dryer container. U.S. Pat. No. 2,827,276 discloses a dryer with a heater contained in a heater box which is supplied with ambient air through an opening in an upper portion of the box together with a baffle for deflecting the heated air into the dryer container. U.S. Pat. No. 3,290,028 discloses a dryer where the hot air from a gas burner is mixed with ambient air in a cooling zone and the mixture then directed into the dryer container.
Although the above prior patents are the most pertinent of which applicants are aware, none discloses a combination including a baffle within a heater box immediately downstream from a heating means adjacent the side of the heater box that is nearest the dryer container and thus subjected to the heat in the container for creating turbulence of the air in a zone between the downstream end of the heating means or heater and the inlet opening to the dryer container with air opening for ambient air in the heater box adjacent the inlet to the dryer container.
As stated above, the invention is particularly important with an expanded metal heating element of the type disclosed and claimed in our copending application Ser. No. 587,436, filed June 16, 1975 assigned to the same assignee as the present application.
The combination of this invention is also particularly adaptable to a compact heater unit in which the heating means, baffle, ambient air inlet and air entrance opening to the dryer container is a compact self-contained unit that forms an air duct for inlet air to the drum of a dryer.